T-Mobile

For a limited time, T-Mobile is offering a BOGO promo on the iPhone 7 through the iPhone X. Buy one iPhone, and you'll receive up to a $700 credit off your second iPhone. A trade-in is required; eligible trade-in brands include Apple, Samsung, LG, and Google. Also, keep in mind that you'll receive your rebate via mail in the form of a $700 prepaid MasterCard. So that means you'll need to pay for both phones upfront while you wait (six to eight weeks) for your rebate.

Verizon

Not to be outdone, Verizon is taking $100 off models of the iPhone X, iPhone 8, and iPhone 8 Plus when customers upgrade to either phone. If you purchase a new iPhone X, iPhone 8, or iPhone 8 Plus and add a new line you'll get $300 off your smartphone purchase. Both offers require a trade-in.

AT&T

Need two iPhones? AT&T is currently offering a BOGO iPhone sale. Purchase and activate a new iPhone on AT&T's Next Plan and you'll receive a $700 credit on your second iPhone purchase. The sale includes the iPhone 8, iPhone 8 Plus, and iPhone X. However, both phones must be purchased on an AT&T Next plan in order to receive your credit on the second phone.

Best Buy

Best Buy is offering all of Apple's iPhones on your carrier of choice (excluding T-Mobile). However, it's not offering Sprint's $8/month iPhone promo, so you're better off buying a Sprint iPhone direct from Sprint if you want to take advantage of that flash sale. If you're a Sprint customer — or plan on being one — Best Buy has the iPhone X for $20/month over an 18-month lease, for a final price of $360. Alternatively, Sprint customers can lease an iPhone 8 or iPhone 8 Plus and get one free. (Phones must be activated with an 18-month Sprint Flex Lease).

Other Carriers

Prepaid carriers Boost, Cricket and MetroPCS offer all three of Apple's new iPhones, but only Boost is offering a promo at the moment. The carrier is taking $100 off the iPhone X, iPhone 8 Plus, and iPhone 8. It's also offering dollar-off discounts on some of Apple's previous-gen phones like the iPhone 6s ($80 off) and the iPhone SE ($190 off).

I was fooled as well with Sprint's iPhone X offer. After calling them, they acknowledged that the real deal is buried in another link. You only get the $20/month if you add another line. The cust. serv. rep even admitted it was deceptive. Not surprised, but disappointed that I fell for it too.